Within theological circles there has, naturally, been unending debate over whether evolution occurs at all (or to any degree explanatory of the state of life on Earth); theological models requiring literal adherence to scriptural accounts of wholesale Creation are inconsistent with the proposition that all life evolved from a single, simple, common ancestor. But, religious views aside there has, as well, been a parallel debate within scientific circles -- a debate over whether there was a single Universal Common Ancestor, or whether there were separate and distinct and independent incidences of abiogenesis leading to the rise of life on this planet, with different such incidences responsible for some different strains of still-existing terrestrial life. Courtesy of the work of one Douglas Theobald, completed in June of 2010, it now seems concluded to a scientific certainty that there is but one common ancestor to which all life on Earth can be traced.

How did Theobald do this deed? He studied numerous species to determine the genetic drift expressed in 23 universally present intercellular proteins -- those are proteins which serve a function restricted to carrying materials within the cell. And, to be crystal clear here, the study did not measure the drift of DNA providing instructions on building a wing or a foot or a lung, but for DNA providing instructions on building a basic protein which exists only within cells, and for which an exactly identical protein would do just as well for every living thing on Earth; the differences serve no purpose, and yet those differences exist and, as Theobald discovered in measuring the drift amongst several dozen of them, they are distributed among all different species of life on the planet in exactly the pattern that would be generated if all those life forms had indeed descended from one common ancestor, and had branched off from that common ancestor exactly when the fossil record suggests they did, and exactly when and other taxonomic and genetic features indicate they did.

Pipes in the Wall

Imagine for a moment that we're speaking of waterpipes buried behind a wall. These pipes might be painted to prevent rust, but it makes absolutely no difference what color the paint is -- if every single one were the exact same shade of green, it would not affect their functioning a bit, nor it they were red or gold or candy-striped. Now suppose you look at the pipes in one house and see that they are indeed green, and all the houses in that neighborhood have identical green pipes, but for some reason if you go 100 mileswest and look at the pipes you start to notice that they are green paint mixed with flecks of gold paint, and if you keep going west the gold gets more and more prominent, until you are six thousand miles away and the pipes are clearly just a greenish gold. If you go north instead you discover that the pipes grow gradually redder; going east you see them become gradually bluer, and going south they darken towards black. Knowing only this much you might conclude that the color of the pipes represent a continuum relating in some way to the first set of pipes (not necessarily the first pipes you saw, but some first set of pipes somewhere from which all the rest have varied in tiny progressions).

Now, how could you test this? Well, pick a spot, say, 200 miles west of where you saw red pipes, and if you are truly on a continuum you should see red pipes flecked with gold; pick a spot 375 miles east of there, or 600 miles southeast, or 1200 miles south-south-west, and you should be able to predict before you get there what color the pipes will be. Or, pick a random spot, look at the color of the pipes, and try to guess from that color where exactly it is that you are at that moment -- and then determine where you are geographically, and see if you correctly divined your location from nothing more than a calculation based on the exact color of the pipe. And this is precisely the continuum which was predicted, and then confirmed, by Theobald's study, with trivial variations of protein structures serving identical functions among living things on a continuum of distance from a common ancestor.

But then, Theobald's study is not so much like drawing such a conclusion from variations in the coloration of a pipe found behind every wall; it is like finding that for 23 different pipes, beams, and wires, every one of which is found behind every wall -- and for which each one, measured independently, shows the same predicted variation from one common ancestor. And, to quote the source, "By plugging these sequences into various relational and evolutionary models, (Theobald) found that a universal common ancestor is at least 102,860 more likely to have produced the modern-day protein sequence variances than even the next most probable scenario."

Penguins and Pine Trees and Polar Bears:

It might be objected, naturally, that an intelligent designer might "re-use" similar proteins from one species to the next, especially, where they were particularly accommodating to the environment in which those things were destined to live. And that would indeed be evidence of intelligent design -- except, that's just not how it turns out to have worked in reality. Penguins and polar bears and pine trees all live in frozen climes, and yet, the DNA of a penguins and tropical birds of paradise are more similar to each other than either is to that of a polar bear or a pine tree, or to any reptile or fish or insect, no matter where it lives; and the DNA of polar bears and desert rats are again more similar to each other than either are to any bird or other class of animals, and moreso again then to plants. The same can be said of deep sea squids and desert scorpions, genetically more similar to each other than either is to any fish in the ocean and to any insect in the desert.

A designer might well use precisely the same 23 proteins if they all work the same; the trouble with that is the discovery that they are simply similar, but not exactly identical; they have trivial variations, as trivial as the different color of paint on pipes behind a wall, when all the shades of paint offer exactly identical functioning. It's not just that these proteins are identical but for tiny, tiny differences, it is that those tiny, tiny differences vary so as to match up precisely to the degree of evolution each living thing has from a common ancestor. And, again, the differences between the proteins have no effect on their functionality at all, zero. They work exactly the same in every case.

And yet, take any two, or three, or ten, or thousand living things, and the compare the genetic drift in any one of these 23 proteins, and it matches the exact degree of separation of these living things from a common ancestor, and from each other (so king penguins and emperor penguins have nonfunctional protein variations that are more similar than either penguin has to ostriches, and all penguins, ostriches, sparrows, and other birds have nonfunctional protein variations that are more similar to each other than those of penguins are to prarie dogs. Humans have nonfunctional protein variations which are more like those of chimps than like those of orangutans, and more like those of orangutans than like those of gibbons, and more like those of gibbons than like those of marmosets, and more like those of marmosets than like those of rats, and more like those of rats than like those of cats, and more like those of cats than like those of anteaters, and more like those of anteaters than like those of ostriches, and more like those of ostriches than like those of geckos, and so forth all the way down the chain of life until we get to plants, fungi, and individual bacteria (all of which also have each of these 23 proteins within their cells, and each of which shows exactly the degree of genetic drift from a common ancestor in every single one of their nonfunctional intercellular protein structures).

And so it goes, for every one of the hundreds of thousands of species on Earth, and for every single one of the trillions upon trillions of living things. There's some special beauty to Theobald's premise in that it is infinitely and eminently replicable. Any scientist anywhere, indeed any person anywhere with the means to examine the structures of proteins existing within the cells of particular species can calculate for themselves whether twelve or twenty or twelve dozen universally exhibited proteins (if there are that many) are distributed in accordance with descent from a Universal Common Ancestor; and undoubtedly these tests will be done, and in this Internet age of instantly uploadable genetic maps, the results will be immediately testable by anyone comparably equipped.

Does Any Alternate Probability Remain?

There are three reasons this circumstance might have come about; one is, naturally, evolution by common descent from a single common ancestor, from which all living things have descended and have branched off in an intelligible taxonomic order; but note that this discovery does not exclude the possibility that life arose at multiple distinct occasions, from which only a single line prevailed to expand and evolve into our contemporary biosphere. This, as numerically noted above, is so much more likely than any other course of events as to eliminate them from reason, though we may still contemplate them for amusement. The second possibility is a level of purerandomchance so ridiculously unlikely that a Universe capable of producing it would have to be insane, and just as likely to pop out of existence altogether in the next instant as to turn everything within it to puddles of potash.

The third possibility is the least likely of them all, for it is almost entirely self-contradictory. That is the possibility of a deity who is incapable of causing evolution by common descent, but who really, really wants to pull out all the stops in creating an unflappable appearance of evolution by common descent. But the ability of such a deity to engage in such a deception would almost automatically suggest sufficient power and intellect to successfully pull off the more intelligent and efficient task of actual Creation through evolution by natural selection.

Even supposing a deity with no power to create actual evolution from a single ancestor, but nonetheless possessing the power of making a wholesale creation complete with dozens of independent markers of genetic drift, all pointing toward a Universal Common Ancestor, there's simply no sense in making trivial changes to internal protein structures in a way which only matches up exactly to one circumstance -- the one which would have occurred if all living things had descended from one common ancestor. The deity that engineered (or, indeed, allowed) such a deception would have to be as insane as the Universe which produced this result randomly.

So, even were we to presume that we exist in a created Universe, so far as the origin of life within such a Universe may be accounted for, this discovery only points in favor of one amongst the deistic models (monodeism, pandeism, panendeism, polydeism, etc), in which the laws of our Universe, set into motion at the outset by a Creator which need never tinker thereafter, lead to all manner of complexity (including biological complexity) now observed.

So, again, kudos to Dr. Theobald for putting the pieces together to show that drift in the structure of proteins common to all living things matches up with the predicted drift from a Universal Common Ancestor for every species tested.